Semi-rigid, low loss coaxial cables enjoy widespread use in cable television distribution systems, for example. Such cables typically include a solid central conductor which is surrounded by a core of low loss, high dielectric characteristic material, usually a plastic foam. A metal, e.g. aluminum, cylindrical outer jacket providing a signal return path concentrically surrounds the central conductor and contains the dielectric material. The cable is protected by a non-conductive sheathing which surrounds the outer metal jacket and prevents moisture from reaching the jacket or the interior of the cable.
In order for the cable to be used effectively, a connector is typically provided for attachment at an end thereof. Once installed, the connector may then serve as an interface between the cable and distribution amplifiers or panels; or, alternatively, the connector may be double-ended and serve as an appliance to splice two cable ends together.
The ends of television distribution semi-rigid coaxial cables are typically prepared by the craftsperson/installer in order to receive the cable connector. Such preparation typically comprises removal of the outer sheathing and metal jacket for about one half inch, and removal with a standard coring tool of the foam core between the jacket and the central conductor for a distance of about one to two inches in order to receive a conductive mandrel against which the outer jacket and sheathing are clamped by the connector. In using connectors the outer plastic sheathing material is removed for some longitudinal distance of cable at the end, so that a split ring ferrule may directly engage and clamp the outer metal jacket to the mandrel.
Cable connectors of the type contemplated by the prior art have usually comprised either three piece or two piece assemblies. A representative three piece cable connector is depicted in FIG. 1 of the Blanchard U.S. Pat. No. 4,346,958, whereas a representative two piece cable connector is depicted in FIGS. 2-4 thereof. Another representative two piece cable connector is depicted in U.S. Pat. No. 4,583,811 which is commmonly assigned with the present patent, the disclosure of which is hereby incorporated by reference.
Two piece cable connectors typically comprise a body which includes a cable engagement mechanism or structure for gripping the central conductor and for connecting to the outer metal jacket of the cable and an interface mechanism or structure for enabling an electrical connection to be made to the connector at an interface, i.e. a jack or junction of associated equipment. An outer nut is then threaded over the body, and compressively engages the cable to accomplish a mechanical attachment thereto, and also an electrical connection to the outer metal jacket and one or more environmental seals between the sheathing and the nut and body of the connector. The process of tightening the nut over the body of the connector may have the consequence of tightening the grip on the central conductor, as was the case in the referenced U.S. Pat. No. 4,583,811. And, when the nut is tightened, a split ring or fingered ferrule becomes compressed and forces the sheathing and outer metal jacket to contact and bear against the mandrel of the connector.
While prior art connector designs have assumed a wide variety of shapes and employed myriad principles, fundamentally, a cable connector must provide positive and secure mechanical and electrical connection. In order to work reliably over extended time periods, it must also achieve an effective, moisture-tight seal with the cable and the ambient in order to prevent intrusion of moisture. Even if an effective electrical connection is obtained at the central conductor and at the outer metal jacket, EMI requirements and regulations insist that radio frequency energies not be able to leak or escape to the ambient at the situs of the connector and cause potential interference with other communications services or appliances. Finally, the cable connector should be easy to install without special skills or tooling and without requiring application of significant tightening torques. Providing a cable connector which satisfies all of the foregoing requirements has proven problematic within the connector art.